The qualitative stage of the evolutionary process is species. Bud- is a collection individuals|individuals that are similar in morphophysiological characteristics are capable of interbreeding, producing fertile offspring, and forming a system of populations that form a common habitat.

Each type of living organisms can be described based on a set of characteristic|characteristic features|traits, properties, which are called signs. Characteristics of a species by which one species is distinguished from another are called criteria kind. The most commonly used are six general species criteria: morphological, physiological, geographical, environmental, genetic and biochemical.

Morphological criterion involves a description of the external (morphological) characteristics of individuals that are part of a certain species. By appearance, the size and color of the plumage can, for example, easily distinguish a great spotted woodpecker from a green one, a lesser spotted woodpecker from a yellow one, a great tit from a tufted one, a long-tailed one, a blue one, and from a chickadee. Based on the appearance of the shoots and inflorescences, the size and arrangement of the leaves, the types of clover are easily distinguished: meadow, creeping, lupine, mountain.

The morphological criterion is the most convenient and is therefore widely used in taxonomy. However, this criterion is not sufficient to distinguish between species that have significant morphological similarities. To date, facts have accumulated indicating the existence of twin species that do not have noticeable morphological differences, but do not interbreed in nature due to the presence of different chromosome sets. Thus, under the name “black rat,” two twin species are distinguished: rats with 38 chromosomes in their karyotype and living throughout Europe, Africa, America, Australia, New Zealand, Asia to the west of India, and rats with 42 chromosomes, the distribution of which is associated with the Mongoloid sedentary civilizations inhabiting Asia east of Burma. It has also been established that under the name “malaria mosquito” there are 15 outwardly indistinguishable species.

Physiological criterion lies in the similarity of life processes, primarily in the possibility of crossing between individuals of the same species with the formation of fertile offspring. Physiological isolation exists between different species. For example, in many species of Drosophila, sperm from individuals of a foreign species causes an immunological reaction in the female genital tract, which leads to the death of sperm. At the same time, crossing is possible between some species of living organisms; in this case, fertile hybrids can be formed (finches, canaries, crows|ravens, hares, poplars|poplars, willows, etc.)

Geographic criterion (geographical certainty of the species) based on the fact that each species occupies certain territory or water area. In other words, each species is characterized by a certain geographical area. Many species occupy different habitats. But a huge number of species have overlapping or overlapping ranges. In addition, there are species that do not have clear boundaries of distribution, as well as cosmopolitan species that live on vast expanses of land or ocean. Some inhabitants of inland bodies of water - rivers and freshwater lakes (species of pondweed, duckweed, reed) are cosmopolitans. An extensive set of cosmopolitans is found among weeds and garbage plants, synanthropic animals (species that live near humans or his dwelling) - bedbug, red cockroach, housefly, as well as dandelion, field grass, shepherd's purse, etc.

There are also species that have a discontinuous range. For example, linden grows in Europe and is found in the Kuznetsk Alatau and Krasnoyarsk Territory. The blue magpie|magpie has two parts of its range - Western European and Eastern Siberian. Due to these circumstances, the geographical criterion, like others, is not absolute.

Ecological criterion is based on the fact that each species can exist only in certain conditions, performing a corresponding function in a certain biogeocenosis. In other words, each species occupies a specific ecological niche. For example, acrid buttercup grows in floodplain meadows, creeping buttercup grows along the banks of rivers and ditches, and burning buttercup grows in wetlands. There are, however, species that do not have a strict ecological association. Firstly, these are synanthropic species. Secondly, these are species that are under human care: indoor and cultivated plants, Pets.

Genetic (cytomorphological) criterion based on the difference between species by karyotypes, i.e., by the number, shape and size of chromosomes. The vast majority of species are characterized by a strictly defined karyotype. However, this criterion is not universal. Firstly, many different types the number of chromosomes is the same and their shape is similar. Thus, many species from the legume family have 22 chromosomes (2n = 22). Secondly, within the same species there may be individuals with different numbers chromosomes, which is the result of genomic mutations. For example, goat willow has a diploid (38) and tetraploid (76) number of chromosomes. In silver crucian carp, there are populations with a set of chromosomes of 100, 150,200, while the normal number is 50. Thus, in the case of the occurrence of polyploid or aneushyoid (the absence of one chromosome or the appearance of an extra one in the genome) forms, based on a genetic criterion, it is impossible to reliably determine the identity of individuals | individuals to a specific species.

Biochemical criterion allows you to distinguish species by biochemical parameters (composition and structure of certain proteins, nucleic acids and other substances). It is known that the synthesis of certain high-molecular substances is characteristic only of certain groups of species. For example, plant species differ in their ability to form and accumulate alkaloids within the families Solanaceae, Asteraceae, Liliaceae, and Orchids. Or, for example, for two species of butterflies from the genus Amata, a diagnostic sign is the presence of two enzymes - phosphoglucomutase and esterase-5. However, this criterion is not widely used - it is labor-intensive and far from universal. There is significant intraspecific variability in almost all biochemical parameters, down to the sequence of amino acids in protein molecules and nucleotides in individual sections of DNA.

Thus, none of the criteria alone can serve to determine the species. A species can only be characterized by their totality.

1. What is a species?

Answer. Species (lat. species) - a taxonomic, systematic unit, a group of individuals with common morphophysiological, biochemical and behavioral characteristics, capable of mutual crossing, producing fertile offspring in a number of generations, naturally distributed within a certain area and similarly changing under the influence of factors external environment. A species is a really existing genetically indivisible unit of the living world, the main structural unit in a system of organisms.

2. What types of plants and animals do you know?

Answer. Types of plants: European swimsuit, Altai anemone, bifolia lyubka, needle-leaved carnation, Lady's slipper, etc.

Types of animals: Brown bear, Siberian roe deer, common lynx, pine marten, black ferret, European mink. striped chipmunk, flying squirrel, gray partridge, black grouse and others.

Questions after § 53

1. Define a biological species.

Answer. Biological species- this is a set of individuals that have the ability to interbreed with the formation of fertile offspring; inhabiting a certain area; possessing a number of common morphological and physiological characteristics and similarities in relationships with the biotic and abiotic environment.

A biological species is not only a systematic category. This is a holistic element of living nature, isolated from other species. The integrity of the species is manifested in the fact that its individuals can live and reproduce only by interacting with each other thanks to the mutual adaptations of organisms developed in the process of evolution: the peculiarities of the coordination of the structure of the maternal organism and the embryo, signaling and perception systems in animals, common territory, similarity of life habits and reactions to seasonal climate changes, etc. Species adaptations ensure the preservation of the species, although sometimes they can harm individual individuals. River perch, for example, feeds on its own young, due to which the species survives when there is a lack of food, even despite the loss of part of the offspring. Each species exists in nature as a historically emerged integral formation.

2. What species criteria do you know?

Answer. The characteristic features and properties by which some species differ from others are called species criteria.

The morphological criterion is the similarity of external and internal structure organisms. Carl Linnaeus, for example, defined species as integral groups of organisms that differ from other life forms based on structural characteristics. In other words, the presence of structural features that make a certain group of organisms similar to each other and at the same time different from all other groups is the criterion for classifying them as a given species.

Individuals within a species are sometimes so variable that it is not always possible to determine the species based on morphological criteria alone. There are species that are morphologically similar. These are twin species that are discovered in all systematic groups. For example, two twin species are known in black rats - with 38 and 49 chromosomes; at malaria mosquito– 6 twin species, a small spined lance fish, widespread in fresh water bodies, has 3 such species. Twin species are found among the most various organisms: fish, insects, mammals, plants, but individuals of such twin species do not interbreed.

The genetic criterion is a set of chromosomes characteristic of each species; their strictly defined number, sizes and shapes, DNA composition. The chromosome set is the main species characteristic. Individuals of different species have different sets of chromosomes, so they cannot interbreed and are reproductively limited from each other in natural conditions.

The physiological criterion is the similarity of the body’s reactions to external influences, the rhythms of development and reproduction. This criterion is based on the similarity of all life processes, and above all reproduction. Representatives of different species, as a rule, do not interbreed or their offspring are infertile. However, there are exceptions. For example, dogs can produce offspring by mating with wolves. Hybrids of some species of birds (canaries, finches), as well as plants (poplars, willows) can be fertile. Consequently, the physiological criterion is also insufficient to determine the species identity of individuals.

An ecological criterion is a characteristic position of a species in natural communities x, its connections with other species, sets of environmental factors necessary for existence.

Geographic criterion - area of ​​distribution, a certain area occupied by a species in nature.

The historical criterion is the community of ancestors, a single history of the emergence and development of the species.

3. What is the integrity of the species, how is it manifested?

Answer. View is a complete system. The view is a single integral system. The integrity of the species is ensured by its isolation from other species due to a specific chromosome set (reproductive isolation).

The integrity of a species is also determined by the connections that its individuals form in populations and subspecies. Relationships between males and females, parents and their offspring, individuals different ages in a flock, herd and colony they allow one to successfully reproduce, take care of offspring, provide protection from enemies, etc. The entire set of connections ensures the existence of the species as an integral system.

4. Why is it important to preserve species in nature?

Answer. Biological diversity on the planet is the presence on it large quantity species of all kingdoms: animals, plants, fungi. The task of preserving them is one of the main ones in ecology. Planet Earth is truly rich, therefore, a person is obliged to protect this wealth, at least so that it goes to the next generations of people. So that grandchildren and great-grandchildren can see wonderful animals, beautiful corners of nature, and can use medicinal plants. Any plant or animal (even the smallest one) is part of the biogeocenosis, and in general, is included in the entire ecosystem of the Earth. The body participates in the cycle of substances, being a link in the food chain. Plants that are producers synthesize nutrients using solar energy. Consumers consume energy accumulated by plants and other animals, deritophages “recycle” dead animals, and decomposers finally decompose nutrient residues. Thus, each organism occupies a certain place in nature and performs a certain role. The disappearance of one link can cause the disappearance of several more, changing the entire chain. There will be not only a depletion of the food chain, but also an imbalance of species in the ecosystem. Some species may increase disproportionately in number and cause ecological disaster. For example, an unprecedented proliferation of locusts can deprive entire regions of crops. By preserving the wealth of species on the planet, we thus maintain the stability of ecosystems and ensure the safety of life of all species, including human life. In addition, scientists want to preserve the genetic information of each species, counting on future technologies that will make it possible to recreate animal world of the past, for example, in isolated recreation areas (parks), to recreate extinct and currently endangered species of animals and plants.

Nature has created the living world in such a way that each type of organism differs from the other in its feeding method, as well as in its territory of residence. If we take birds, for example, we can see that there are visible differences between tits, chickadees, and blue tits in the choice of insects to provide food for themselves, as well as in the processes of obtaining food. Some people look for food in the bark of a tree, while others look for food in the leaves of plants. Moreover, they all belong to the genus tits.

Of course, the ecological criterion is not multifunctional in terms of characteristics, because science has proven that some animals various types may have identical properties according to this criterion. For example, they all eat small crustaceans, and their lifestyle is also the same, although they live in different seas.

What is a species?

Let's look in detail at what sam means. In the scientific world, it involves a collection of living beings and plants that have the ability to interbreed with each other and also have offspring.

The species falls under the definition since today it represents precisely a group of related organic formations that have the same root cause of occurrence, but in this moment they are endowed with certain characteristics of a morphological, physiological and biochemical nature, separated by natural or artificial selection from other species groups and adapted to a specific habitat.

Formation of new species

How are views created? - the main engines of the formation of new types. In the first case, the emergence of qualitatively new family groups and orders is implied, which appeared as a result of long-term microevolutionary changes. In the second, a complex process of mutations occurs, which gradually separate entire families and orders, forming new species. And in this case they become a separate complex of organisms.

That is, thanks to microevolution, which is also defined as “supraspecific”, species become even more separated in their qualities, transforming into groups with the same set of characteristics. This can be understood using the example of the ecological criterion of a species: there is also a durum variety, which means, in a general sense, this is a genus of wheat, and there are grains of rye, wheat and barley, and all of them are representatives of the cereal family. From this we can conclude that all samples of any families descended from some common ancestor, thanks to microevolutionary processes that occurred in the population of this ancestor itself.

What does the ecological criterion of a species consist of?

The definition is the complex effects of environmental traits on a species in its range. These characteristics are divided into groups: biotic factors (when living organisms influence each other, for example, by pollinating plants by bees), abiotic factors (the influence of temperature, humidity, light, relief, soil, water salinity, wind, and so on on the development of living organisms ) and anthropogenic factors (human impact on the surrounding flora and fauna).

All species of the animal and plant world develop constructive signs of adaptation to environment during evolution, and the nature of the habitat is the same for the entire species. What examples of an ecological criterion for a species can be given if we consider it from this point of view? The unity of the species is associated with the free crossing of individuals. Plus, historical development shows that over time a species may develop completely new adaptation, for example, giving certain signals to each other when a situation arises, or the appearance of group protection from enemies.

An example of an ecological criterion for a species would be isolation. That is, when the same species has different ecological conditions, the differences in their behavior and morphological structure will be significant. A good illustration is urban and rural swifts. If they are put in one cage, then there will be no offspring, because during their lives in different environmental conditions, individuals of this species have developed various morphological, physiological and other characteristics. But they continue to remain under the "roof" of the same species, and this is an example of the ecological criterion of an animal species.

Flora in ecological criteria

Examples of the ecological criterion of a species in plants are those that can form several ecotypes, some of which will live in the plains and others in the mountains. These include, for example, St. John's wort, some species of which, thanks to microevolution, quickly adapted to new growing conditions.

The influence of the external environment on the evolution of a species

The famous researcher Lamarck believed that the greatest influence on a living organism is the inorganic environment, that is, its physical and chemical compositions(temperature, climatic conditions, water resources, soil composition, and so on). Everything that came under their influence could change the types of living organisms, giving them characteristics inherent in a given ecological niche. Due to forced adaptation, the animal (plant) began to change, thereby forming the new kind or subspecies This can be called an example of an ecological criterion for a species.

Temperature conditions within the framework of environmental criteria

An example of a species according to ecological criteria can be a living organism adapted to different temperature conditions. During adaptation, a biochemical change occurs internal organs and fabrics. Due to the fact that animals can live in low, high or fluctuating temperatures, they are divided into groups: cold-blooded, warm-blooded and heterothermic.

Considering that the sources of heat are both external and internal factors, then, considering the first group using the example of lizards, one can notice that they prefer to bask in the sun rather than hide in the shadows. This means that their internal ability to thermoregulate is very low. Being under a heat flow, they increase their body temperature quite quickly. However, by evaporating the accumulated moisture, the lizard can reduce it to a comfortable level. Such species are organisms of lower development. But despite this, exist with low temperatures They won't be able to do it without external heat.

From examples of biology: the ecological criterion for a species of the warm-blooded group includes almost all mammals and birds. Thermoregulation in their bodies occurs on the physical (breathing, evaporation, etc.) and chemical (metabolic intensity) levels. In addition, warm-blooded organisms can tremble, thereby increasing their body temperature; in animals with feathers and underfur, thermal insulation occurs when they are raised. In the face of cold wind or hot sun, such organisms have to look for an alternative: shade of coolness or good shelter from frostbite.

The third group is an intermediate stage between the first two. This usually includes species of primitive animals and birds, as well as those living organisms that have their own period of hibernation, that is, they themselves can control body temperature, lower or increase it. As an example, we can take the marmot, which in winter, when hibernating, lowers its body temperature to six degrees, and during the active period of its life it increases to human temperature.

The influence of soil on the development of the species

Besides climatic conditions, Very important for the species has the soil environment of its range. In this case, representatives of underground inhabitants can be taken as an example of an ecological criterion for a species. Little “diggers” have only one function for survival - to dig their home as best and deeply as possible so that no predator can reach them.

They use their limbs, which are adapted to a certain type of soil, that is, with a change in place of residence in the form of soil, the limbs must adapt over time. All living organisms like a mole have a similar paw structure, and living underground has adapted the animal to a lack of oxygen and suffocation, and this is an inevitable situation.

The importance of precipitation using the example of an environmental criterion of the type

Creatures that have adapted to snow cover, frequent rainfall, hail, high humidity, and so on have special differences in the structure of the body. In biology environmental criterion species will be a change in animal cover to match the color of the snow. This happens in birds, hares, for example, a white partridge actually turns white, changing its feather plumage.

Winter “clothes” are much warmer, and constant exposure to snow increases heat transfer. How? It turns out that under the thick snow the air temperature is much higher than outside it. Therefore, hibernating bears survive the winter well, spending the night in snowy dens. To move through snow, organisms develop special devices on the limbs, be it sharp claws for walking on ice or webbed feet for moving through tropical flooded forests.

Since the ecology on the planet is constantly changing, the processes of microevolution, during which living beings adapt to new living conditions, continue.

1. Morphological criterion is characteristic features and properties by which some species differ from others. Example: Darwin's finches. Varieties of finches are distinguished by morphological criterion - the structure of the beak. The ground finch has an elongated beak and a split tongue. The large ground finch has a thick, powerful beak.
2. Physiological criteria- it is based on the similarity of all life processes, primarily the similarity of reproduction, which determines the possibility of offspring during crossing. For example, in many species of Drosophila flies, the sperm of individuals of a foreign species causes an immune reaction, which leads to the death of sperm in the female genital tract. At the same time, there are species in nature whose individuals interbreed and produce fertile offspring.
3. Cytological criterion - a set of chromosomes characteristic of each species, their size, shape, DNA composition. For example, some species of the legume family have 22 chromosomes.
4. Ecological criterion - the place of a species in natural communities of organisms, its specialization, sets of environmental factors necessary for the existence of the species. Example: For example, acrid buttercup grows in floodplain meadows, creeping buttercup grows along the banks of rivers and ditches, and burning buttercup grows in wetlands. There are, however, species that do not have a strict ecological association. Firstly, these are synanthropic species. Secondly, these are species that are under human care: indoor and cultivated plants, pets.
5. Geographical criterion - the area of ​​distribution of the species in nature. Example: Some inhabitants of inland bodies of water - rivers and freshwater lakes (species of pondweed, duckweed, reed) are cosmopolitans. An extensive set of cosmopolitans is found among weeds and garbage plants, synanthropic animals.
6. Historical criterion - community of ancestors, a single history of the origin and development of the species. Various criteria are interconnected and only together determine the integrity and unity of the species. For example, the Wolf evolved from carnivorous predators. They lived on earth about 100 million years ago. Much later, namely about 20 million years ago, dogs evolved from the wolf. Dogs and wolves descended from miacids, which lived on earth 50 million years ago.
The wolf emerged as a species about 1 million years ago. By the end of the Pleistocene period, it became the most common predator.
7. Ethological criterion - In the behavior of individuals of most species, there are certain specific characteristics that also characterize the species, as well as morphological, ecological and other characteristics. Differences in behavior between closely related species are primarily observed during the mating season. In the behavior of individuals of most species, there are certain specific characteristics that also characterize the species, as well as morphological, ecological and other characteristics. Differences in behavior between closely related species are primarily observed during the mating season. For example, it is enough for a male of one of the species of Far Eastern plovers, living together with another closely related species, to jerk his tail not three, but twice (which is typical for another species), and the female will no longer allow this male to approach her

What are the species criteria? Name and characterize the main criteria of the species.

Species criteria are characteristics and properties characteristic of a species. None of the criteria is absolute, but their complex is evidence of the reality of the species.

The morphological criterion of a species determines the similarity of the external and internal structure. However, the presence of lookalike species (mosquitoes, aphids, etc.) sometimes complicates its use. At the same time, individuals of the same species can differ in appearance. For example, some animals and birds exhibit sexual dimorphism (male and female individuals are different).

The physiological criterion of a species characterizes the similarity of the life processes of individuals of the same species. It is also not accurate enough. Most species in natural conditions do not interbreed or their offspring are sterile, but there are exceptions - a number of species of canaries, poplars, etc.

The biochemical criterion of a species is based on the ability to synthesize specific proteins. This is due to a unique DNA sequence.

Genetic - shows that species differ in the number and structure of chromosomes.

Ecological - each species exists in certain conditions. For example, creeping buttercup in damp places, and caustic buttercup in dry meadows.

Geographic - determines the habitat of the species, its range. Each species has a specific range.

What are the species criteria? Name and characterize the main criteria of the species.

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